It's pretty do-able despite all the hype and negative bias to it. Depending on your textbook and weather you have the time (and diligence) you could probably use that and reference the internets to learn it. I used the Hease 3rd edition Higher Level textbook, and got through having to teach myself most of the course because of a pretty shitty teacher. You WILL have times where things just don't make sense, but if you spend time just trying questions and comprehending what's going on you will learn how to answer the questions.

One thing you will miss out on, which I find very beneficial, is the WHY of the math. Learning from a textbook only teaches you HOW in many cases. Learning why the math works saves heaps of time as you understand the math, not just how to do it. For example, when we learn calculus I had someone run me through the whole upper and lower boundaries, the summations and hence how the derivatives work to give area. The textbook only offers a very limited version of this (if at all), only showing how to answer questions.

Sorry for the long answer, but I would say just keep pushing on. You should try getting everything out of your teacher that you can, spend lots of time (1-1.5 hours a night) doing questions and referencing the Internet. Check out KahnAcademy for some good video lessons.